Composition and electrical conductivity of some cobaltates of the type La2−xSrxCoO4.5−x/2±δ

摘要: Abstract A series of La 2− x Sr CoO 4.5− /2± δ ( =0.5–1.5) compounds as powders and ceramic shapes were prepared by solid state reactions. All compositions show a single-phase K 2 NiF 4 -type structure within the whole temperature region (X-ray investigation at 20–1000°C in air). Reversible oxygen desorption–sorption behaviour argon during heating cooling between 300 1050°C was observed. The amount exchanged oxygen, , found to be function content, : from 0.5≤ ≤0.8 decreased zero 0.9≤ ≤1.5 it increased maximum value. stoichiometry changes occured range solution corresponding reaction Co 3+ O /2 ⇔La 1− 3±1 ± /2O . equilibrium values electrical resistivity LaSrCoO 4± =1) investigated (400–1050°C) partial pressure p =2.9–286 Pa; 21 000 Pa). log σ −log dependence point p-type conductivity had slope 1/10 400–1000°C. Above 850°C coefficient changed negative one with 160 S cm −1